Reduced-
antigen-content
pertussis vaccines designed initially for booster vaccination of adolescents and adults can also be used to vaccinate pre-school age children.
Combination vaccines, which reduce the number of administered
injections, combine multiple
antigens including inactivated poliovirus (IPV), which is recommended in this age group in some countries. This randomised, controlled study compared a combined
diphtheria-
tetanus-acellular
pertussis-inactivated
polio-containing booster
vaccine,
dTpa-IPV (
Boostrix Polio, n=822), to separately administered
dTpa (
Boostrix) and IPV (IPV Mérieux, n=136) in 4-8-year-old children who had previously received four doses of
DTPa. Additional serological assessment was performed 1 year after the booster dose. One month after vaccination, seroprotection/
vaccine response rates were similar for both groups. At least 99.9% of the subjects had protective
antibodies against
diphtheria,
tetanus and
polio, and at least 90.1% had a
vaccine response to
pertussis antigens after
dTpa-IPV. Reactogenicity of
dTpa-IPV was comparable to
dTpa + IPV.
Fever and grade 3 loss of appetite occurred more commonly after
dTpa-IPV, whereas swelling and grade 3
pain occurred more frequently after separately administered
dTpa + IPV (P<0.05 for all). However, 95% CIs overlapped in all cases. Large swelling reactions after
dTpa-IPV occurred less commonly than have been reported after a fifth dose of
DTPa. One year after the booster, 98.6% of the subjects tested continued to have protective
antibodies against
diphtheria,
tetanus and
polio, and at least 81.2% were seropositive for
pertussis components. The reduced-
antigen-content
dTpa-IPV
vaccine was immunogenic, well tolerated and safe in pre-school age children. It provides immunity against four diseases in a single injection, with the potential reactogenicity benefit of a reduced-
antigen dose.